Finder.



J. BECKER.

FINDER.

APPLICATION man DEC. 13. 19.16.

1,289,088. Patented Dec. 31,1918.

Inventor UNITED STATES PATENT OFFICE.

JOSEPH BECKER, OF WASHINGTON, DISTRICT OF COIJZI IMIBIA, ASSIGNOR TO EASTMAN KODAK COMPANY, OF ROCHESTER, NEW YORK, A CORPORATION OF NEW YORK.

FINDER.

Specification of Letters Patent.

Patented Dec. 31, 1918.

Original application filed February 17, 1905, Serial No. 246,169. Divided and this application filed December 13, 1916. Serial No. 136,684.

fication. D

My present application for patent, 1dent1- fied for convenience of reference as Case As, is Division five of my prior application Case J, Serial No. 246,169, filed February 17, 1905 (now Patent 1,210,137,, issued December 26, 1916). It relates to certain features of said Case J which are separately patentable under the head of Finders.

The present specification hereinafter refers more or less specifically to my other related patent applications as follows: Case C, now Patent 1,178,476, issued April 4,

1916; Case G, Serial No. 110',299, filed June 5, 1902, now abandoned, inview of prlor publications cited in the appended notes, but again prosecuted, for all parts thereof thereof that are novel and patentable, in the present Case As as Division five of my copending and above mentioned parent Case J; the said Case J now Patent 1,210,136, LIS- sued December 26, 1916; Case Ah or division I of C, now Patent 1,210,134, issued December 26, 1916; Case An, Serial No. 124,832, filed October 10, 1916, continued as, and merged in, Case A0 or Division one of J, now Patent 1,210,137, issued December 26, 1916; Case Ap, or Division two of J, Serial No. 133,162, filed November 24, 1916, allowed February 7, 1918; Case Aq or Division three of J,

Serial No. 136,293, filed December 11, 1916, allowed March 2, 1918; Case Ar or Division four of J, Serial No. 136,428, filed December 12, 1916, allowed February 7, 1918.

The present invention relates mainly to the sight directing elements of the divergent lens finder with .grazed rear sight, first disclosed b me in Figures 4 and 5 of my then in several of the original but now .canceled figures of my said Case J,

which are now reproduced as Figs. 1 to 9 of my said allowed Case Aq.

As fully explained in my said Case Ah (page 1, lines 41 to 52), a finder of the divergent lens type, more particularly one in which the lens is eccentric, is incomplete and inoperative unless it is provided with some special means for determining the direction of its line of sight; and this sighting means should preferably be provided with adjust-' ments adapted to produce slight angular variations in the sighting direction, so that errors of construction, principally errors in lens grinding, may easily be compensated or corrected, in the finally assembled combina tion of camera and finder, by a simple regulation of the said sighting direction.

Three different modes of adjusting or regulating this sighting direction have already been disclosed in my said prior Cases Ah, Aq and Ar; but the present application, Case As, discloses a fourth method of adjustment which has special advantages in those forms of the finder that determine the sighting direction, as inFigs. 4 and 5 of my said Case G, or as in Figs. 1 to 9 of said Case Aq, by means of a rear non-pro ecting stationary sight that is formed in, or directly on, the rear or plate-holding part of the camera and *which is intended to be just grazed by the refracted group of finder rays that'proceeds from the distant camera field, through the finder, to the observers eye.

The rear sight, in such combinations, asv already explained in descrlbing the said- Figs. 5 to 9 of my said Case Aq, can easily be shifted along such sighting edge for corto the'said sighting edge; but it can not conveniently be displaced in any direction that is perpendicular to such edge.

My present invention, therefore, compensates or corrects such errors of eccentricity by bodily adjustment or displacement of the finder lens itself, in the transverse direction that is substantially perpendicular to the direction of the said rear sighting edge.

My four diflerent adjustments here re ferred to, for correcting the direction of the line of sight, may. briefly be described and clearly distinguished, as follows:

My first method of adjustment or correction is most clearly disclosed in Fig. 1 of my said Case Ah, where the adjustable slantrecting errors of centering that are parallel ing direction of the line of sight is determined by means of a forward virtual or image sight V" lozated centrally in the incidental group of finder rays; and the sight ing direction is corrected or adjusted (as explained on page 2, lines 69 to 89, of said Case Ah) by shifting the position of this forward sight V" in any desired direction that is substantially perpendicular to the axial vector 6 V. In this type of finder' the refracted group beta (6) of finder rays that proceeds from the finder to the observers eye e. passes at a considerable distance above the rear part 23 of'the camera.

My second method of adjustment or correction is disclosed in Figs. 10 and 11 of my said allowed Case'Aq, where the adjustable slanting direction of the line of sight is determined by means of a fence-like rear sight 203; and the sightin direction is corrected or adjusted by longitudinally shifting the position of this fence-like rear sight 203 until it is just grazed by the refracted group alpha (0:) of rays that proceeds from the finder lens to the observers eye.

My third method of adjustment or correction is disclosed in Fig. 12 of my said allowed Case Aq, and also in my said Case Ar,

. Where the same slanting direction of sight is determined by the head of a screw 310,10-

cated centrally in the refracted group of finder rays to serve as a rear central bead sight; and the sightin direction is corrected or adjusted, by changing the position of this rear central bead sight.

My fourth method? of: correction or 'ad justment, constituting the gist of the main invention claimed in the present applica tion, Case As, provides correcting adjustment in the line of sight by changing or'adjusting the position of useof the finder lens. This feature proves specially valuable in combinations such as seen in Figs. 4 and 5 of my said Case G, or Figs.'1 to 9 of my said Case Aq, where the finder ,comprises a rear sight that is absolutely fixed and that is intended to be just grazed by the refracted group of finder rays that proceeds from the distant camera field, throug the finder, to the observers'eye.

The present invention, therefore, consists mainly in a specially. simple and effective means for adjusting or changing the position of use of the finder lens, so that a non projecting point P, fixed on the rear or plate-holding part of the camera, may surely be used as an arcuate rear sight for the said finder lens, in cooperation with the marked central part M of the lens, acting as central sight. .My invention further consists in designing the arrangement so that the depth of the' finder, as measured alon M P, of the central nder ray, shall be substantially equal to the depth of the camthe internal part,

era, as measured alongthe internal part, M P, of the central camera ray, so that the finder lens, rigidly connected to the camera lens, will automatically be moved with the camera lens, to suitably change the direction of the finder field, whenever the camera lens is moved-transversely to change the direction P M of'the camera field, a principle that was first fully disclosedjn my said Case G as applied to the centric divergent lens finder.

In the accompanying drawings:

Fig. 1 is a face view of a bellows camera with the invention applied thereto, and

Fig. 2 is a side view of the same, mounted on a tripod and sectioned sufficiently to show the inside construction of the finder parts.

The camera when opened up for use com prises a rigid L-shaped frame 20, 21. The

vertical member .20 of this frame serves more or less directly as the support for the sensitized plate or film, whose center is .indicated at P.

The camera objective 22, whose second nodal point is indicated by M, is mounted on a lens board 23 which is adjustable verti cally between grooved uprights 24, 25, whose lower ends are rigidly connected by the horizontal member 26, and this is provided with a dovetail cleat 27 adapted to.

The eccentric lens 31, here shown single,

but preferably made; as a doublet as in my said Case Ap, is firmly mounted in a rectangular box-like frame 32, which is provided with a tail piece 33 by means of which the finder is adjustably fastened to the lens board 23. The tail piece 33 is provided with a slot 34 for the admission of a clamp screw 35, and it also has a hole for the admission of a screw 36, which is only inserted, as a permanent fastener, after the proper adjustment of the finder lens 31 on the lens board'23 has been found. 2

' The finder is first temporarily fastened in place by screw 35 so it can be slid about and will remain where set, and the cameracamera plate or film. The finder mount 32 a is then raised or lowered until the same ob ject shall appear centrally at M in the finder lens 31 when the observer places his eye at the proper elevation to just see the bottom llne of the finder field in coincidence with the upper edge of the plate holding part 20 of the camera. The screw 36 is then inserted to permanently fix the finder in place and screw 35 may also be screwed home firmly.

The operator finally notches or otherwise marks the camera frame at 15, 16, just opposite his eye, in order to determine the lateral direction of the line of sight. The middle point of this notch is indicated by P.

Uo-oaryz'ug finder and camera. fields.

In accordance with the principles of my.

said Case G, the variable line M P remains constantly of very nearly the same length as the variable line M P, so that when the objective is shifted in any direction parallel with the plate, the camera field and finder field are both changed indirection by equal angles. Changes in the horizontal direction are accurately equal in both fields. Changes in the vertical direction als correspond exactly enough for all purposes if the focusing dis lacements are relatively small.

0 take advantage of the more exactly operating of these changes when the lens has to be raised or lowered, the camera need only be turned so that its present horizontal dimensions shall be vertical. This change mightbe useful even if the camera has a reversible back, as the object of the turning it is to use the more accurately working crosswise adjustment in place of the needed vertical adjustment.

Norr. 1.The geometrical and optical principles involved in the present application Case As are substantially the same as given for the centric finder in my said Case G.

No'rn 2.The invention of my said Case G, however, was substantially anticipated in the.S ido hand" camera of Gaumont, described 1n L Nature, Paris, June 17, 1899, pages 41 1: 42; Fig. 3 on page 41; text in the lastfour lines of page 41, and the first seventeen lines of page 42. I

NOTE 3.The La Nature descri tion of Note 1, was reproduced in the c'ient'ific American Supplement, New York, Novem be 11, 1899,.page 19955, Fig. 3; last twentyone lines of column two, and first seventeen lines of column three.

NOTE 4.The Gaumont hand camera was also described on page 140 of the-Fabre Aide Me'moz're do Photographic pou/r 1901, Paris, 1900. No'rn 5. A device also closely resembling that" of my'Case G is that-of Gillon described, but not illustrated in the Bulletin ray.

dela Sooz'e't Frangae'se de Photographic, Paris, 1901, pages 89 and. 90. Copy at the Library of Congress.

No'rn 6.-In view of documents cited in Notes 2 to 5, I do not make any broad claim for directionally changing the line of sight in a finder of the divergent lens type; but, in view of the theoretical disclosures made in my said Case G, I do claim the applicability of the same principle to a lens of the eccentric lens typebecause such applicability is not obvious, for two different reasons, to wit: first, because the direction, P M, of the central finder ray cannot be made parallel to the direction, P M, of the central camera ray; and, secondly, because the central finder ray of an eccentric lens, being no longer an axial ray of the lens, is bent by the lens, and such bend is variable with the inclination of the incidental partof such NOTE 7 .The Gillon device of Note 5, or one closely resembling it, is shown and de scribed in La Nature, Paris, April 20, 1901, vol. 29, pages 328-329; and particularly Fig. 2 (-1) on page 329, with text in the last 14 lines of page 328, first 14 lines of page 329, and first 7 lines of column 2 of page 329.

NOTE 8.'.lhe La Nature article of Note 7 is reproduced in the Scientific American.-

direction, and that carries an eccentric lens which is alleged to bea finder lens. Clark, however, shows no means whatever for determining the direction of the line of sight of-this finder lens; and without such means the combination is, as pointed out above, ino erative; moreover, the Clark central fin er ray, indicated-by a dotted line in his Fig. 2, has the incidental, or right hand, part thereof inclined at about 18 degrees, or oneefi'fth of a right angle, whereas, in

accordance with my lnvention, this same incidental part (ray X M A in my Fig. 2)

should be horizontal, assumin the camera lens to be in its normal 'IJOSllJlOIl of use or placed as shown in Fig. 2 of Clark, and in my resent Fi 2.-

TE 10. rom disclosures made in my said Case G, 1t appears that preservation of the identity of the camera and finder fields, is perfect, both as to extent of field and direction of field, for all changes inthe depth, M P, of'the camera, as well as for all changes in the inclination-of axis,

M P, on the camera plate, only when the finder lens is of infinite focal length; that is to say. only when the finder lens is a plain glass plate of the same size as the camera plate; or When it is the equivalent of the open frame or window finder surrounding said plate; or, finally, when it is similar to the wire frame-finder seen in Figs. 1 and 10 of U. S. Patent 365,435, issued June 28, 1887, to Freeman. The Freeman specification makes no mention of this remarkable property of his wire frame finder; but a geometrically more perfect form of the same type of finder, possessing all of its here referred to automatic field preserving properties, in their highest degree of perfection, was fully disclosed by Huilliard in the Bulletin ole Za Sooz't F rangaise de Photographic, Paris, 1900, pages 173 to 175,Figs. 1 and 2,. (copy at the Library of Congress).

My said Case G, furthermore, proves that the centric divergent lens finder, as compared With the finder of Freeman or Huilliard, is much less efficient in preserving extent of field, but equally-eficient in preserving direction of field.

No'rn 11.In using adjustment 34: the operator, judging solely by the result, simply moves the lens, up or down, until he has brought the central point of the distant camera field into apparent alinement with the middle point M of the finder Window; and this simple operation is entirely independent of the amount of eccentricity that may be present in the glass lens. The invention is, therefore, directly applicable, Without any modification Whatever, to, the centric finder seen in Figs. 4 and 5 of my said Case G; and claim 1 hereinafter made is, accordingly, not limited to eccentric lenses.

No'rn 12.Where the eccentricity of the finder lens is relatively large, the focusing displacements of the camera lens will, as a general rule, and in the present type of fixed rear sight finder, produce ob ectionable variations in the sighting direction of the finder field; hence where such focusing displacements must themselves be relatively large, the eccentricity of the finder lens should not be made larger than necessary.

What I claim as my invention, and desire to secure by Letters Patent, is

1. The combination with a photographic camera having a finder of the divergent lens type, with a rear sight marked or formed directly on an external edge of the camera frame, lying parallel and relatively close to an edge of the inclosed plate or film; of

means for holding said finder lens in its position of use; and means for changing a dimension in said lens-holding means, to permit ofchanging the said position of use, in a transverse direction that is substantially perpendicular to the said sighting edge, so that the refracted group of finder rays that proceeds from the relatively distant camera field through the said finder maybe moved transversely With said-finder lens, and be causedto pass grazingly by the said rear sight.

2. The combination with a photographic camera comprising a plate or film-holding part, and an objective holding part, and means for transversely changing the relative position of said tWo parts, so that the inclination of the internal part, M P, of the central camera ray, may be turned from its normal position with relation to the plate or film, to' an abnormal or inclined position; of a finder, for said camera, comprising two parts, to Wit: first, an eccentric lens produced in the direction of the said finder field.

, In testimony whereof, I have signed my name to this specification. JOSEPH BECKER. 

